Posts Tagged instrumentation

If I can get off the hook with “It’s what the clock says”, we’re done here. Otherwise?.

Here’s the thing. Lots has been written about this. It get pretty deep out there, believe me. We humans figured out how to count time by using something that moves continuously and uniformly such as the moon traveling around the earth as a proxy for time. Twice as far meant twice as much time had gone by. Distance traveled equaled time. It’s the idea behind clocks (the old fashioned kind) where the hands rotate around the face of the clock and time is marked off along the edge.

You can see that this doesn’t tell us a thing. What does uniform mean?

It has been suggested that time represents a change in “entropy” (how much is left of the way things were ordered or “wound up” when the universe started). If that’s true, time started when the universe started. But maybe time stretches out beyond the end of the universe and before the beginning. Maybe there was time before “the first second”.

I’m not supposed to say that, am I?

We’re still unraveling that mysterious first fraction of a second of the “Big Bang” when, supposedly, there was infinite density. Few physicists believe that there was any such a thing. Getting smaller than the “Planck length” ( 10 to the minus 35 meters) may not be physically possible. So something else might have happened other than a so-called singularity. Maybe there were events “before”. Before? Doesn’t that mean there was time?

Some say that there is an illusional quality to time. That we perceive something that isn’t there. That the physical world is sliced up into very small “ticks” making the time dimension granular instead of continuous. All that was, and all that will be, is captured in each of these ticks like frames in a movie film.

I could go on and on but I’m afraid I will mislead. This is a lovely and fascinating area for discussion, but I shouldn’t take take up your valuable time for this. The subject goes deeper than my own brain goes.

You’ve got an $8.95 laser pointer from Job Lot. You had some hair removed by a laser. There’s one in your CD player. And they’re inside of things that’re all over your house. You even use one to drive the cat WACKY. And I wish you wouldn’t.

SAME PAGE-INESS

I’ll take a minute here to explain the difference between a laser and, say, an electric light.

Until 1958, when the laser was invented at Bell Labs, all forms of artificial light were “incoherent”. Incoherent light consists of light waves that don’t “line up” particularly well. The crests and the valleys of the waves are “all over the place” as opposed to coherent light where all the crests and valleys DO line up with each other.

What’s the difference? When light is coherent, it behaves itself. Instead of spreading (converging), it remains packed into a tight beam.

Not much of a difference, I admit. But it makes the light kinda “pure” and “monochromatic” (one and only one frequency) as opposed to a flashlight which is a great big MESS of frequencies. And a laser light doesn’t spread out the way we’re used to a light beam behaving; instead it just stays in a tight beam. The science behind it is NICELY described in an article in HOW STUFF WORKS. Which I appreciate because MISTER ScienceAintSoBad is in NO mood to go through all the details, this morning.

The fact that monochromatic laser light DOESN’T dissipate its energy by spreading out like its more ordinary cousins means it can transmit great power over a long distance or offer real accuracy for measuring stuff. Its nice tight beam is even useful for communications since it can illuminate light fibers or bounce off of distant targets and still hold onto its properties.

Who would a thought that a laser, which is, after all, just a humble beam of light, would turn out to be so important?

WHY USE SOUND?

The length of a light wave is short. It’s measured in billionths of a meter. Wanna see how the wavelength varies with color? (Probably not, but just in case, this is fun. )

Frequency, for frequency, the wavelengths of sound are even shorter. Much, much shorter. So sound could be used for WAY more accurate measurements in medicine and other applications. And a sound-based laser (phonon laser) would, no doubt, have other startling tricks it could do besides measurement, if we really had one.

THE PHONON LASER

Phonon lasers still aren’t available at Job Lot but the work’s movin’ along VERY nicely. It’s described in Physical Review Letters (who NAMES these publications?) and in Physics.

Mister ScienceAintSoBad thinks the emergence of the phonon laser is now likely. Whole new industries will follow.